[OP]
Member
I have the opportunity to purchase a large 40hp dust collector for a heck of a deal. I have the necessary 3 phase power requirements. Only problem is that it is a cyclone based system intended to go outdoors and blow the dust into a dumpster.
Is there any way to redirect the exhaust air back into the shop? I don’t want to loose my conditioned air and need to find a solution. I am not really sure if this is possible or what it would take to make it an indoor dust collector. Any thoughts?
Contributor
That is much bigger than any I have experience with. A second stage filter is used after the cyclone for the indoor units I have worked on. The biggest one has a series of hanging felt bags. It would take a big bank of filters for 40 HP. Blowing into a bin or dumpster is mostly for very coarse sawdust, shavings, and chips.
A brand new, big, commercial shop, in Des Moines had the steel siding suck in and crumple the first time they ran a system that big.
Last edited by Maurice Mcmurry; 04-21-2022 at 8:00 AM.
Best Regards, Maurice
Moderator
Doing what you want to do with that big system may be tough...large industrial systems are designed differently, not just in size but for how the backend works. OSHA rules are extremely strict at this point for "inside the shop filtration", which is why so many of these big, industrial systems are setup for outdoor material disposal including the air. So even if it seems like a "deal" financially initially, it may not be a "deal" to you when all is said and done.
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The most expensive tool is the one you buy "cheaply" and often...
I did the electrical for a collection system that had 2, 50HP motors. Before returning the air to the shop space, it was filtered in a bag house. It had 10 individual bag compartments, each with 5 or 6 bags. Each compartment had a high pressure fan that was to force reverse flow through the bags to clean them. The control system ran the fans one at a time. The spoil was carried to an airlock & dumped into a dumpster.
It worked very well with no noticeable drops in air volume. Until a hot bit of something made its way into the bag house and burned the whole thing out in just minutes, in spite of the sprinkler system. At least the fire spread no further and they just had to clean it up & replace the bags.
Moderator
40hp?! Are you buying this for your home? A system 1/10 that size is large enough for a home shop. What is “heck of a deal” ? I can’t imagine it would be much cheaper than a top of the line, new cyclone at 3-5hp…
[OP]
Member
They have a 10hp unit for sale too. Might get it instead. LoL. How would I do this with a 10hp cyclone setup?Originally Posted by Jim Becker
Contributor
You can build a plenum and buy tube filters from a vendor like us Air Filtration or American Filter Fabric, but filtration for a 40hp system is going to be expensive. Also, fire codes are strict about controls on a system that big returning air into a shop. Imagine a spark in the filter bank being fanned by a 40 hp blower. You would probably need a spark detector, extinguishing system and automatic abort gate for a system that size. Talk to the fire marshal and a professional system designer. You really need to design a system around your specific requirements. Buying a 40 hp blower and cyclone if a 10 hp system would suffice doesn't make sense.
For comparison, the shop I used to work at has a 15 hp system rated somewhere around 6,000 cfm. It has a 16" intake duct and about 600 sq. ft. of filters in a configuration that is very hard to clean. The shop is about 5,000 sq. ft. and has probably 20 drops from 4" to 6". It works reasonably well, but it lacks the safety controls mentioned above and if they ever do get a fire in the system that old barn will be ashes in short order. I wonder what the insurance co. would do in that scenario. It was a "bargain" when it was installed (used) 35 years ago, but and expensive to retrofit or replace with proper equipment.
I seem to remember you posting about ductwork options for your shop not long ago. Have you done the calculations necessary to come up with the correct blower size?
Last edited by Kevin Jenness; 04-22-2022 at 7:42 AM.
Moderator
The specific machine matters...I'm not trying to dance around this for sport, either, as I have no knowledge of the system(s) you're considering working with. Something from Oneida or Clearvu is where most folks' wheelhouses are here in the forums relative to capable cyclone dust collection systems and the majority of people don't have anything larger than "5hp". I do remember one community member that (I believe) has a big. 10hp Grizzly in his shop but it was designed for indoor use.
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The most expensive tool is the one you buy "cheaply" and often...
Contributor
A cigarette is the usual suspect. Are any contributors Fire Fighters?
There was a fire where I worked in 2000, caused by an unattended Watlow heater. When I heard the news my first thought was "Cigarette". All of the work benches in that shop were adorned with cigarette burns. The sprinklers did their job on the fire. The water damage to the floors below did its job on the company. : (
Best Regards, Maurice
Contributor
I doubt if that was the case there. Back then there was smoking inside, but strictly forbidden in the shop for obvious reasons. The thinking was that a piece of wood had jammed in the works somehow and a shower of sparks headed up the duct.
Member
If the dust collector is running at 40hp it's also going to generate a lot of heat (30+kW) that will need to be dealt with in the summer.
Perhaps it would be possible to restrict the airflow such that the motor would be running at a more manageable 5hp.
Contributor
Exhausting it outside in summer would be the answer to the heat. Even blocking the inlet entirely would not bring it down to 5HP. I bet getting the load down to 20HP is probably as low as it would go.
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